Firstly, let me show you wat he does...
The guy at work insisted there was a mirror involved... but there's no mirror
basically there's a guy hidden above the camera, he's holding Mr Squiggle's tall hat from above, and the hidden guy looks down onto the paper and draw, to him, the picture is right way up, but to us, its upside down...
then at the end the lady turn the picture around for us to see it...